Carburetor throttle control assembly

ABSTRACT

A single-ended control arrangement for the butterfly spindle in a carburetor, in which a speed governor shaft is geared to one end of the spindle while the other end is sealed off, and an accelerator element is connected through a spring to the shaft to influence together with a governor vane the rotation of the shaft.

United States Patent Glover et al.

[ Feb. 8, 1972 [54] C ARBURETOR THROTTLE CONTROL ASSEMBLY [72] inventors: Peter David Glover; Richard Forshaw; William Henry Steele, all of Milperra, New

South Wales, Australia [73] Assignee: Victa Limited, Milperra, New South Wales, Australia [22] Filed: May 1,1970

'21 Appl. No.: 33,583

[30] Foreign Application Priority Data Mar. 31, 1970 Australia ..l3,l81/70 US. Cl ..123/l03 B ..F02d 31/00 FieldofSearch ..123/103 B, 119, 179 A, 179 B,

123/ l79 BG [56] References Cited UNITED STATES PATENTS 2,935,977 5/1960 Eberline ..l23/l03 B X 2,964,028 12/1960 Wiles 1 23/103 Primary Examinerl.aurence M. Goodridge Attorney-Wenderoth, Lind & Ponack [57] ABSTRACT A single-ended control arrangement for the butterfly spindle in a carburetor, in which a speed governor shaft is geared to one end of the spindle while the other end is sealed off, and an accelerator element is connected through a spring to the shaft to influence together with a governor vane the rotation of the shaft.

5 Claims, 4 Drawing Figures PAINTED FEW 8W SHEET 1 UF 3 alsaozsa WW0 FER elm 3.640253 SHEET 1% BF 3 5/ I F H G IHVLLIJIORS PLTLLP. DAVID GLOIEP RICHARD FORSH/ar/ WLLLIAM HENRY Il'lHfuLi-J CARBURETOR THROTTLE CONTROL ASSEMBLY This invention relates to carburetor throttle controls and more particularly to assemblies of this kind which incorporate speed governing means for'an associated engine.

invariably, due to the amount of required linkages, carburetors incorporating such features have their spindles mounting a butterfly valve controlled at both ends, frequently with governing means connected at one end and accelerator control at the other. When such assemblies are incorporated in a carburetor upon a lawnmower difficulties arise in providing adequate sealing of the butterfly spindle in the foul air conditions which often exist.

It is the principalobject of the invention to provide an improved form of throttle control assembly incorporating a speed governor, preferably one that is compact and has improved sealing.

in one general form of the invention there is provided a throttle control assembly for a carburetor having a butterfly control valve mounted within a housing upon a rotatable spindle, said assembly comprising a governor vane on one end of a shaft rotatable upon the housing and extending substantially normal to the butterfly spindle, gearing interconnecting the shaft with one end of the spindle, a rotatable accelerator element surrounding the shaft, manually controlable linkage to the accelerator element, resilient means connecting the accelerator element to the governor vane to relay through the tension of said resilient means accelerator control to the butterfly valve, and means for sealing off the other end of the spindle.

A preferred form of the invention is illustrated in the accompanying drawings, in which:

FIG. 1 is a fragmentary plan view of a typical lawnmower engine showing the carburetor mounted thereon with the throttle control arm fully displaced so as to open the throttle butterfly valve with the engine cutout switch in the open position;

PK]. 2 is an exploded perspective view of the relevant com ponent parts of the carburetor;

FIG. 3 is an outer end elevation of the carburetor only showing the throttle control arm and butterfly valve fully closed and the engine cutout switch closed; and,

FIG. 4 is a front elevation of the carburetor only with the cover removed from the bevel gear housing. 1

The carburetor 5 is mounted on the air intake port 6 of an engine cylinder7. A throttle butterfly valve 8 is mounted in the carburetor throat 9 in the recess 10 of a spindle l1 and is held in place by a setscrew 12. The spindle 11 is rotatablyv mounted in bearings 13 and 14 on each side of the throat 9, The bearing 13 is closed by a polyethylene cap 13A which is a press fit in the bore of the bearing 13 and keeps dust excluded from this end of the spindle 11. The other end 15 of the spindle 11 mounted in the bearing 14, passes into a housing 16 and a bevel pinion 17 is mounted on the end of the spindle 11 within the housing 16. A tubular extension 18 extends vertically from and integrally with, the roof 19 of the housing 16. A vertical shaft 20 is rotatably mounted within the bore 21 of the extension 18. A bevel gear 22 is mounted on the lower end of the shaft 20, within the housing 16, and said gear 22 meshes with the pinion 17.

The upper end 23 of the shaft 20 is drivably connected to a throttle control arm 24 through an adjustable torsion spring mechanism 25 in the manner described in our copending application Ser. No. 24,129 and no further description seems necessary. The outer end of the control arm 24 is provided with an integral boxlike housing 26 which is adapted to receive a U-shaped strip 27 which forms one pole of an engine cutout switch. A rectangular opening 28 is formed in one side of the housing 26 to receive the strip 27. One leg 27A of the strip 27 is bent inwardly to form a step which snaps behind the opening 28 to lock the strip 27 in place when it is pushed into the opening 28. A cylindrical pin 29, which forms the other pole of the engine cutout switch, is mounted in a radial barrel 30 extending medially from the housing 26. A flange 31 is formed near the outer end of the pin 29 and is accommodated in an enlarged bore 32 in the barrel 30. A compression spring 33, formed from a nonconductive plastic material is also mounted in the bore 32, and normally forces the pin 29 away from the strip 27. The free end 34 of the pin 29 is bored to receive the end 35 of a bowden cable 36 which extends to the throttle lever (not shown) on the handle of the mowing machine to which the engine cylinder 7 is filled.

In FIG. 1 the bowden cable 36 has pulled the throttle control arm 24 to the position shown in which the butterfly valve 8 is fully open. The spring 33 will act so as to force the pin 29 away from the strip 27 and the engine cutout switch will therefore be open.

When the bowden cable 36 is moved so as to swing the arm 24 to the other extremity of its travel as shown in FIG. 3, the throttle butterfly 8 is closed. The engine 7 will continue to run however as, an air bleed hole 37 is provided in the butterfly I valve 8 so that sufficient mixture reaches the engine 7 to enable it to run at idling speed. The control arm 24 is engaged by a stop 38 on the extension 18 in this idling position. Further pressure on the bowden cable 36 cannot therefore displace the arm 24, but will instead force the pin 29 into contact with the strip 27, against the action of the spring 33. The engine cutout switch is thus closed. A flexible lead 39 secured to the longer leg 40 of the strip 27 connects said strip to the primary winding of the engine magnet 41. The winding is thus earthed through the body of the carburetor 5 and the engine 7 stops.

It will be seen that the housing 16 is provided with a cover 42 which is secured to theface 43 of the housing by setscrews 44. A. gasket 45 is interposed between the cover 42 and housing face 43 so that no dirt can enter the carburetor 5 from this side of the throttle butterfly spindle 11. The other end of the said spindle 11 is protected from the ingress of dirt by means of the cap 13A. This is a distinct improvement on previous carburetors in which the corresponding butterfly valve spindle always projected through both sides of the carburetor throat, and into the atmosphere. Dirt could therefore not be excluded so that wear took place in spindle bearings. The extra air admitted to the carburetor via'the worn bearings upset the fuelair mixture ratio and rendered the engine difficult to start.

What we claim is:

1. In an internal combustion engine having provision for a cooling air stream, a carburetor comprising a housing, an induction throat within the housing, a butterfly valve within the throat, a spindle rotatably supported in a bore in the housing and extending across the throat and carrying said valve, means for closing one end of the bore against the ingress of dust to a first end of the spindle, a control shaft geared to a second end of the spindle, a governor vane fixed on the shaft for angular deflection by the engine-cooling airstream, a manually controlled accelerator element rotatable about the shaft, and resilient means interconnecting the accelerator element and the shaft to permit rotation of the shaft under influence of the governor vane independent from rotation of the accelerator element.

2. In an internal combustion engine as claimed in claim 1, wherein the gearing between said control shaft and said spindle is enclosed within a compartment sealed by a removable cover.

3. In an internal combustion engine as claimed in claim 1, wherein said housing includes an extension above the gearing between said control shaft and said spindle, and said control shaft is rotatably mounted therein.

4. In an internal combustion engine as claimed in claim 1, wherein a control arm is provided on said accelerator element and carries a housing, electrical switch means mounted in said last-named housing, and a control cable is attached through said switch means to said control arm, said switch means being connected with the electrical system of the engine to stop the engine when operated.

5. In an internal combustion engine as claimed in claim 4, wherein said electrical switch means is a pair of contacts separated from each other by spring action, and an end of said cable connects to said control arm through one of said contacts so that a drawing force applied to said cable serves to move said control arm to close said butterfly valve and upon further application of a drawing force to said cable closes said contacts against said spring action. 5

I 3! II 

1. In an internal combustion engine having provision for a cooling air stream, a carburetor comprising a housing, an induction throat within the housing, a butterfly valve within the throat, a spindle rotatably supported in a bore in the housing and extending across the throat and carrying said valve, means for closing one end of the bore against the ingress of dust to a first end of the spindle, a control shaft geared to a second end of the spindle, a governor vane fixed on the shaft for angular deflection by the engine-coolinG airstream, a manually controlled accellerator element rotatable about the shaft, and resilient means interconnecting the accelerator element and the shaft to permit rotation of the shaft under influence of the governor vane independent from rotation of the accelerator element.
 2. In an internal combustion engine as claimed in claim 1, wherein the gearing between said control shaft and said spindle is enclosed within a compartment sealed by a removable cover.
 3. In an internal combustion engine as claimed in claim 1, wherein said housing includes an extension above the gearing between said control shaft and said spindle, and said control shaft is rotatably mounted therein.
 4. In an internal combustion engine as claimed in claim 1, wherein a control arm is provided on said accelerator element and carries a housing, electrical switch means mounted in said last-named housing, and a control cable is attached through said switch means to said control arm, said switch means being connected with the electrical system of the engine to stop the engine when operated.
 5. In an internal combustion engine as claimed in claim 4, wherein said electrical switch means is a pair of contacts separated from each other by spring action, and an end of said cable connects to said control arm through one of said contacts so that a drawing force applied to said cable serves to move said control arm to close said butterfly valve and upon further application of a drawing force to said cable closes said contacts against said spring action. 